Many types of spinal irregularities can cause pain, limit range of motion, or injure the nervous system within the spinal column. These irregularities can result from, without limitation, trauma, tumor, disc degeneration, and disease. Often, these irregularities are treated by immobilizing a portion of the spine. This treatment typically involves affixing a plurality of fixation devices to one or more vertebrae and connecting the devices to an elongate rod that generally extends in the direction of the axis of the spine.
Treatment for these spinal irregularities often involves using a system of fixation devices to attain stability between spinal segments. Instability in the spine can create stress and strain on neurological elements, such as the spinal cord and nerve roots. In order to correct this, implants of certain stiffness can be implanted to restore the correct alignment and portion of the vertebral bodies. In many cases, a fixation device along with a vertical solid member can help restore spinal elements to a pain free situation, or at least may help reduce pain or prevent further injury to the spine.
Typically, fixation devices may include a bone fastener (e.g., bone screw, hook, etc.) for coupling the fixation device to vertebra. Fixation devices further may include a coupling element (e.g., a tulip element) for coupling the bone fastener to the vertical solid member (e.g., elongate rod). Clamp and/or wedge elements may be used to secure the bone fastener in the coupling element. A locking cap may be used to secure the rod in the coupling element.
In order for the elements of the fixation device to be secured, the rod may need to be seated firmly in the coupling element. A variety of methods may be used to maximize engagement between the rod and the coupling element. As one example, in an open surgery, a physician may be able to manually push the rod in contact with the coupling element. However, in other situations, such as in a minimally invasive or percutaneous procedure, it may be more difficult for the physician to view and/or maneuver the rod. In these types of situations, the physician may use a tool such as pliers, forceps, and/or a rod reducer to restore the rod to a proper position securely within the coupling element.